The present invention relates to a pharmaceutical composition for a nasal transmucosal delivery, comprising a biologically active peptide, which is sparingly soluble in water, conjugated with an active biocompatible polymer.
More particularly, the present invention relates to the pharmaceutical composition containing the biocompatible polymer-biologically active peptide conjugate suitable for use in the nasal transmucosal delivery, which is highly improved in water solubility and protected from being degraded by protease.
The pharmaceutical composition comprising of the peptide-polymer conjugate for the nasal transmucosal delivery of the present invention allows drug activity to be expressed in a short period of time and improves bioavailability.
In the body, various peptides play important roles, existing as various forms such as hormones and cytokines. With recent great advances in genetic engineering, various peptides have been able to be synthesized on a mass scale and be used as medicines.
Use of peptides or proteins as medicines, however, suffers from many problems. First, peptides or proteins are very low in body absorption efficiency because they are easily hydrolyzed or degraded by enzymes within a short period of time after being taken into the body. Further, when such peptide medicines are repetitively administered, immune reactions are frequently induced to produce antibodies which may cause so serious hypersensitivity as to menace the life of the administered, acting as a neutralizing role against the physiological activity of the medicines. In addition, the clearance attributable to the reticuloendothelial system (RES) is increased. Therefore, most of peptide medicines have been administered by injection, thus far.
Injection administration, however, gives patients pain and has accompanying dangers. Particularly, patients who need to be treated for a long period of time may not be able to treat themselves by injection. Thus, there remains a need to develop other routes for peptide administration.
An adult""s nasal cavity is coated with a mucosa at a thickness of 2.0-4.0 mm (Mugind, Nasal Allergy, Blackwell Scientific, Oxford, 1979) and has a volume of about 20 ml. It is thought that the nasal cavity allows drug activity to be expressed in a short period of time because of its being abundant in fine villus and large in absorption surface area. Accordingly, extensive research has been made on the transmucosal delivery of drugs. Factors which have influence on the absorption of drugs through mucosae include physical and chemical properties of drugs, such as drug""s inherent transmittance, ion strength, flow distribution coefficient and molecular weight, carrier transportation, protease degradation, and physiological conditions of nasal mucosae. In fact, the nasal mucosa is a direct absorption route through which drugs can circumvent the liver metabolism, which is a great hindrance to the utilization of drugs in the body upon oral administration. Thus, the nasal transmucosal route has an advantage over the oral route in that the body utilization of drugs can be significantly improved.
The nasal transmucosal delivery of peptides or proteins of large molecular weights are lower in absorption efficiency than intravenous injection because the peptides or proteins cannot pass well through nasal mucosae. Absorption promoters have been suggested to improve the absorption of peptides.
Examples of suggested absorption promoters include surfactants (Hirai et al., Int. J. Pharm. 9, 165-169, 1981), acylcarnitine, cholinester, alpha-cyclodextrin, and chelating agents (Lee, In: Delivery Systems for Peptide Drug, Plenum, New York, pp 87-104, 1986).
These absorption promoters, however, are difficult to apply in practice because they give rise to a decrease in the stability of the drugs upon formulation, or irritate nasal mucosae.
In regard to the nasal transmucosal delivery of drugs, many research results are disclosed in patents.
European Pat. Nos. 23,359 and 122,023 open the possibility that a powder formulation of peptide drugs is delivered through nasal mucosae. U.S. Pat. No. 4,250,163 discloses a mucosa-adsorptive substance which is admixed with a powder form of peptides drugs to enhance the nasal transmucosal delivery of the drugs. European Pat. No. 123,831 is directed to the administration of steroids through nasal mucosae.
German Pat. No. 2,620,446 describes a body absorption enhancer which is effective for the nasal transmucosal delivery of insulin.
PCT/GB/86/00721 discloses a formulation technique of drugs into microspheres which can be delivered through nasal mucosae. However, this formulation technique can be applied only to particular drugs.
In Japanese Pat. No. Sho. 58-189118, cyclodextrin is utilized for the nasal transmucosal delivery of peptides. Japanese Pat. No. Sho. 59-89619 discloses ethereal surfactants, for example, polyoxyethylene lauryl ether, as neutral absorption enhancers for nasal transmucosal delivery. However, these surfactants are not suitable for clinical use because they cause damage to nasal mucosae.
Japanese Pat. No. Sho. 61-118325 describes alkaline or neutral amino acids for use in the nasal transmucosal delivery of calcitonin. In Japanese Pat. No. Sho. 63-39822, sucrose fatty acid ester is used as an absorption promoter for the nasal transmucosal delivery of drugs. However, these absorption promoters are also toxic to mucosae.
The above-mentioned reference patents, most of which are based on the sustained release of peptide drugs, enable drugs to be released continuously, but cannot solve the problem that peptides or protein drugs administered through mucosae are degraded in a short period of time. These conventional techniques find difficulty in being applied for the nasal transmucosal delivery of peptide drugs.
Conjunction of pharmaceutically active proteins or molecules to synthetic macromolecules may afford great advantages when they are applied in vivo and in vitro. When being covalently bonded to macromolecules, physiologically active molecules may be changed in surface properties and solubility. For example, their solubility in water or organic solvents may be increased. Further, the presence of macromolecules may make the conjugated peptides more stable in vivo as well as reduce the clearance attributed to the intestinal system, the kidney, the spleen and/or the liver. Hence, conjunction of polymers to peptides can bring about a great improvement in the stability of the peptides in solutions and effectively protect the intrinsic surface properties of peptides to prevent non-specific protein adsorption.
U.S. Pat. No. 4,179,337 discloses conjugates between peptides or polypeptides and polyethylene glycol (hereinafter, referred to as xe2x80x9cPEGxe2x80x9d) with a molecular weight of 500-20,000 or water-soluble polymers, which are reduced in antigenicity and anti-immunity while maintaining the biological activity of the peptides or polypeptides. It is described in U.S. Pat. No. 4,301,144 that hemoglobin is increased in oxygen molecule-carrying potential when being associated with PEG or water-soluble polymers.
Various proteins are reported to show extended half-life spans and reduced immunogenicity in plasma when being conjugated with PEG (Abuchowski et al., Cancer Biochem. Biophys., 7, 175-186, 1984). Uricase-PEG conjugates are demonstrated to be increased in in-vivo half life span and show reduced side-effects during the metabolism of uric acid (Davis et al., Lancet, 2, 281-283, 1981).
As apparent from the preceding patents, the conjugation of PEG allows biologically active peptides or proteins to be increased in-vivo half life span and solubility and to be reduced in immune reactions.
Most frequently, the conjugation of PEG to polypeptides is achieved by reacting activated PEG to amino residues of polypeptides. Suitable for use in this purpose are a lysine residue and N-termini. As for PEG activation, one of the hydroxy groups of PEG is substituted with a methyl ether group while the other hydroxy group is bonded to an electrophile functional group (Abuchowski, A. and Davis, F. F. (1981), in Enzymes as Drugs (Holsenberg, J. and Roberts, J., eds.)). Examples of activated polymers include PEG-N-hydroxysuccineimide-activated esters, which contain amide bonds, PEG-epoxides and PEG-tresylate, which contain alkyl bonds, PEG-carbonyl imidazole and PEG-nitrophenyl carbonates, which contain urethane bonds, PEG-aldehyde, which contains a Schiff""s base at the N-terminus.
On a polypeptide sequence, lysine residues are randomly located, so that PEG is non-specifically bonded to the polypeptide. In order to obtain uniform PEG-peptide conjugates, there have been made attempts of bonding PEG to targeted sites such as cysteine residues, oligo sugars, hydroxy groups, arginine groups.
Examples of PEG derivatives able to specifically react to cysteine groups of polypeptides include PEG-vinyl sulphone, PEG-iodoacetamide, PEG-maleimide, and PEG-orthopyridyl disulfide with most preference to maleimide-containing PEG. PEG-vinyl sulfone is best in view of the stability in water solutions while PEG-orthopyridyl disulfide can be reversibly degraded in vivo because of the presence of disulfide bonds.
Peptides taking advantage of these derivatives can be exemplified by interleukin-3 and interleukin-2.
PEG derivatives reactive specifically to oligo sugars of polypeptides may be exemplified by PEG-hydrazide, which is able to react with aldehyde-containing compounds to form relatively stable hydrazone bonds. Advantage is taken of the specific bonding of PEG-hydrazides to sugar moieties of glycoproteins.
PEG-isocyanates react specifically with hydroxy groups of polypeptides. In order to conjugate PEG to arginine residues of polypeptides, there is used PEG derivatives containing phenylglyoxal, which is highly reactive to the guanidino group.
As mentioned above, the nasal transmucosal delivery of peptides alone is significantly improved in absorption efficiency compared with the oral administration because the peptides are not subjected to liver metabolism, but poor in the bioavailability of the peptides because they are degraded by endogenous enzymes.
To overcome the foregoing and other disadvantages, we, the inventors of the present invention, have developed a pharmaceutical composition for the nasal transmucosal delivery, comprising a sparingly soluble, biologically active polypeptide conjugated with an activated biocompatible polymer. The present invention have confirmed that, when the polymer-peptide conjugate is administered through the nasal cavity, it is improved in water solubility and protected from being degraded by proteases, whereby the medicinal activity of the pharmaceutical composition can be sustained for an extended period of time in vivo.
It is an object of the present invention to provide a biologically active peptide-polymer conjugate suitable for use in a nasal transmucosal delivery.
Further objects and advantages of the present invention will appear hereinafter.
The present invention provides a pharmaceutical composition for the nasal transmucosal delivery, comprising a sparingly soluble, biologically active polypeptide conjugated with an activated biocompatible polymer.
Further features of the present invention will appear hereinafter.